Re: C++ pushback

From: Alexander E. Patrakov
Date: Thu Apr 27 2006 - 05:09:17 EST


J.A. Magallon wrote:
Tell me what is the difference between:


sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
sb->s_fs_info = sbi;
memset(sbi, 0, sizeof(*sbi));
sbi->s_mount_opt = 0;
sbi->s_resuid = EXT3_DEF_RESUID;
sbi->s_resgid = EXT3_DEF_RESGID;

and

SuperBlock() : s_mount_opt(0), s_resuid(EXT3_DEF_RESUID), s_resgid(EXT3_DEF_RESGID)
{}

...
sbi = new SuperBlock;
if (!sbi)
return -ENOMEM;

apart that you don't get members initalized twice and get a shorter code :).

The second example is simply incorrect, because the operator new throws an exception when we run out of memory, instead of returning a null pointer.

So it has to be written as:

sbi = new SuperBlock;
/* The rest of code assumes that the sbi pointer is valid. If this was not the case, let's hope that the caller caught std::bad_alloc properly */

--
Alexander E. Patrakov

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/